1. Field of the Invention
This invention relates to improvements in devices generally known as expansion chambers or otherwise known as hydraulic or pneumatic cylinders. More particularly, it is concerned with the type of device which, under the pressure of a fluid, causes a rod, connected to a piston, to move longitudinally, commonly coaxially, relative to a surrounding cylindrical chamber.
2. Description of the Prior Art
The mechanical advantage of expansion chambers of the type also known as a piston and cylinder have been known for some time. They include the internal combustion engine and hydraulic devices for earth moving equipment, automobile jacks, cranes, and many other types of equipment, including elevators.
Although it is often unimportant, devices in which a rod is rigidly fixed to a piston which moves within a cylinder under fluid pressure are limited by the fact that the travel of the cylinder or piston rod is limited to the length of the internal chamber of the cylinder. Therefore, if it was desired to have an extended length of travel, it would be necessary to provide an equally long cylinder which often provides problems where there is inadequate room. Thus, hydraulic cylinders are rarely found to be useful in the design of elevators of any substantial height.